Waterproof footwear including a waterproof (i.e. impermeable to liquid water) water vapour permeable membrane, such as that available under the GORE-TEX trademark, has been on the market for some time. This has been produced by first of all forming a "bootee" of a laminate of the membrane material, which can then be leak tested by immersion in water. However, it has more recently been proposed to integrate the waterproof membrane into the construction process of the shoe. In this latter case, it becomes necessary to carry out the leak testing on an assembled or partially assembled shoe, rather than a flexible bootee. There is in any case a benefit in being able to leak-test the shoe in its semi-finished state prior to application of the sole. At this stage any leaks can still be corrected. Any test apparatus must, of course, be capable of giving rapid test results in a production line environment.
U.S. Pat. No. 4,799,384 discloses a bootee testing machine wherein the entrance to the bootee is sealed by clamping together the flexible sides of the ankle portion of the bootee. This is only applicable to flexible booties and cannot be used to leak-test assembled or partially assembled shoes.
U.S. Pat. No. 4,918,981 discloses an apparatus for measuring the moisture vapour transmission rate through the sides of a shoe, which involves inserting a waterproof water-vapour-permeable liner inside the shoe, filling the liner with water and measuring the amount of water lost in a given time by transmission through the walls of the liner and the shoe.
It is an object of the present invention to provide an apparatus for leak testing waterproof footwear, which may be used on assembled or partially assembled items of footwear.